Question

If the amplitude of a sound is tripled, What will be the effect on its loudness?

• A. Increases four times
• B. Decreases four times
• C. Increases six times
• D. Decreases six times

Answer 1

The correct option is C Increases six times

The loudness of sound depends on its amplitude. Loudness is proportional to the square of its amplitude.
So, loudness $\propto$ (amplitude)${}^2$

Here amplitude of sound is tripled,

loudness $\propto$ $(3\times amplitude$)${}^2$
loudness $\propto$ $(3{)}^2$$\times (amplitude$)${}^2$
loudness $\propto$ $9$$\times (amplitude$)${}^2$

Hence, if the amplitude of a sound is tripled, loudness increases nine times.